To combine two stages of optical matrix switches to constitute an optical switch by specifying a combination method of the optical matrix switches.

The optical switch 100 is provided with (n) input ports, (m) 1×r optical switches 125a and (r) input side optical switches 125a containing n×m optical switches switching routes of respective input ports and respective 1×r optical switches 125a, and (n) output ports, (m) r×1 optical switches 125b and (r) output side switches 102c containing m×n optical switches switching the routes of respective output ports and respective r×1 optical switches 125b. The i-th 1×r optical switches of respective input side switches 102a are connected to i-th r×1 optical switches of respective output side optical switches 102c. At this time, (m), (n) and (r) are positive integers, and (I) is an integer of 1≤ and ≤r. Thus, by the combination of two stages of optical matrix switches, the optical switch is constituted.